Conventionally, there is known an infrared sensor that includes an infrared detecting device, a package housing the infrared detecting device, and a semiconductor lens closing a window hole, in front of the infrared detecting device, of the package (e.g., JP Pub. Nos. 2011-220939 (Patent Document 1), 2007-292721 (Patent Document 2) and 2010-237117 (Patent Document 3)).
In the infrared sensor, there is a concern about degradation in detection precision because an off-axis aberration occurs in a case where infrared (an off-axis light) emitted from an off-axis object point is detected.